单选题：Living in the central Australian desert has its problems,___..

Those were the graduate assistants ______ to do the research work in the lab.A．to whom it was their responsibilityB．whose responsibility there wasC．whose responsibility wasD．of whom with the responsibility

Far from perfect though this trip is, I think it’s well worth _____ we paid.A．thatB．whatC．whichD．How

“___ comes back home first should cook lunch, ”Mum said.A．WhateverB．WhoeverC．WhoeverD．Whichever

You’d better choose someone____ you think ___ kind and friendly to help you.A．whom; to beB．who; isC．that; isD．which; to be

Today the public is much concerned about the way _______ .A．nature is being ruinedB．which nature is ruinedC．on which to ruin natureD．of nature to be ruined